Chronic infections of West Nile virus detected in California dead birds

William Reisen, Kerry Padgett, Ying Fang, Leslie Woods, Leslie Foss, Jaynia Anderson, Vicki Kramer

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

During 2010 and 2011, 933 recently deceased birds, submitted as part of the dead bird surveillance program, tested positive for West Nile virus RNA at necropsy. The relative amount of RNA measured by qRT-PCR cycles ranged from 8.2 to 37.0 cycle threshold (Ct) and formed a bimodal frequency distribution, with maxima at 20 and 36 Ct and minima at 28-30 Ct. On the basis of frequency distributions among different avian species with different responses to infection following experimental inoculation, field serological data indicating survival of infection, and the discovery of persistent RNA in experimentally infected birds, dead birds collected in nature were scored as "recent" or "chronic" infections on the basis of Ct scores. The percentage of birds scored as having chronic infections was highest during late winter/spring, when all birds were after hatching year, and lowest during late summer, when enzootic transmission was typically highest as indicated by mosquito infections. Our data indicated that intervention efforts should not be based on dead birds with chronic infections unless supported by additional surveillance metrics.

Original languageEnglish (US)
Pages (from-to)401-405
Number of pages5
JournalVector-Borne and Zoonotic Diseases
Volume13
Issue number6
DOIs
StatePublished - 2013

Keywords

  • Chronic infections
  • Dead birds
  • Overwintering
  • Surveillance
  • West Nile virus

ASJC Scopus subject areas

  • Infectious Diseases
  • Microbiology
  • Virology

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